A conventional domestic fan typically includes a set of blades or vanes mounted for rotation about an axis, and drive apparatus for rotating the set of blades to generate an air flow. The movement and circulation of the air flow creates a ‘wind chill’ or breeze and, as a result, the user experiences a cooling effect as heat is dissipated through convection and evaporation. The blades are generally located within a cage which allows an air flow to pass through the housing while preventing users from coming into contact with the rotating blades during use of the fan.
WO 2009/030879 describes a fan assembly which does not use caged blades to project air from the fan assembly. Instead, the fan assembly comprises a cylindrical base which houses a motor-driven impeller for drawing a primary air flow into the base, and an annular nozzle connected to the base and comprising an annular mouth through which the primary air flow is emitted from the fan. The nozzle defines an opening through which air in the local environment of the fan assembly is drawn by the primary air flow emitted from the mouth, amplifying the primary air flow. The nozzle includes a Coanda surface over which the mouth is arranged to direct the primary air flow. The Coanda surface extends symmetrically about the central axis of the opening so that the air flow generated by the fan assembly is in the form of an annular jet having a cylindrical or frusto-conical profile.